HowTo (schema.org)
The schema.org type HowTo is used to mark up step-by-step instructions in a structured way. It brings practically no visibility in Google Search any more, since Google discontinued the corresponding rich results in 2023; as a schema.org type it continues to exist unchanged.
In practice
In August 2023 Google removed HowTo rich results from search and deleted the corresponding documentation – there has been no special display with a step preview since. The HowTo type itself has not been marked as deprecated by schema.org and can still be used, but at present it produces no SEO benefit in the form of rich snippets. Anyone considering investment in new HowTo markup should know this and, in case of doubt, put the resources into more effective types such as FAQPage or Article.